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Polyacrylamide gel electrophoretic analysis of amplified polymorphic STR loci has proven to be a mainstay of forensic and paternity testing. Using this procedure with an instrument such as the Hitachi FMBIO^® II Fluorescent Scanner, large number of samples can be processed simultaneously and the data can be easily interpreted. One drawback with this technique has been the time and expense to prepare the gel and clean the glass plates after each experiment. Disposable gels reduce the preparation time but are expensive and have short shelf lives.

To reduce this drawback, a simple technique has been developed to allow reuse of gels while effectively eliminating the previous samples from the gel. With this technique, a gel has been successfully reused 10 times over a 4 day period. Except for the first and last lanes, the second and third runs are as good if not better than the first run. The bands continue to remain sharp on subsequent runs but edge effects (frowning of the outside lanes) become progressively worse and ultimately limit gel reuse if more than 3/4 of the gel is to be analyzed.

For two runs, no additional gel preparation is necessary. Following the initial run and scan, the gel is run in reverse 15 minutes longer than the forward run to remove the first set of samples and warm the gel for the second run. Samples are then loaded and subjected to electrophoresis as in the first run. The second prerun and run can be done on the same day or the gel can be stored for use days later. More extensive reuse of the gel requires degassing of the gel solution and bonding of the gel to both plates to prevent separation of the gel from the plates.

This technique has been used successfully with a variety of combs and gel sizes. While it does not eliminate the need to prepare polyacrylamide gels, it provides an easy way to reduce the gel preparation of between two and 10 fold. Complete protocols will be provided at the presentation.